Tag: chemistry stockroom

List of materials found in a typical high school or college chemistry stockroom and laboratory that based on respective MSDS sheets, should be stored in a fire cabinet, hazardous materials cabinet, or corrosive materials storage cabinet.

Storage and Safety in High School Chemistry Classrooms and Laboratories is of utmost importance to the students, staff and parents.

One of the more tedious things for a secondary science educator is to properly maintain and take inventory of their chemical stockroom. This needs to be done every couple of years for effective safety measures. It is a well-known fact that certain chemicals should be stored in certain areas, and many of these hazardous chemicals may need to be stored separately within said safe storage vessel. After taking inventory in my stockroom with the help of some of my upper level students, I compiled what my total inventory consisted of, along with the conditions each chemical was in, shelf life of each chemical, and where it is safely stored. In this post, you will find a glossary of the types of chemical and compounds that need to be stored in an OSHA compliant storage cabinet. This post will be broken down into two main categories of chemical based on their proper storage area. A brief description of each chemical, along with its inherent hazards based on MSDS sheet will also be provided.

According to OSHA (Occupational Safety and Health Administration) and the NFPA (National Fire Protection Association) Flammability ratings are as follows:

Flammability (Red Label)

4

Danger

Flammable gas or extremely flammable liquid

3

Warning

Flammable liquid flash point below 100°F

2

Caution

Combustible liquid flash point of 100° to 200°F

1

Combustible if heated

0

Not combustible

If a chemical has flammability ratings of 1-4, it must be stored in an OSHA compliant fire safety container. The following is what my classroom currently stores in terms of flammable materials. All of these materials are stored in a Flammables Cabinet.

Acetone: Dimethyl ketone, or more commonly referred as Acetone, is an extremely flammable Solvent used in numerous chemical applications. It is a great solvent in the lab (which translates to great for cleanup after lab exercises) and is used in gas chromatography as well. It is an extremely flammable category 2 liquid. Also causes eye and respiratory problems if directly exposed.

Amyl Alcohol: Also commonly referred to as Pentyl Alcohol, is a class two flammable organic alcohol. It is commonly used as a solvent to dissolve resins and some oily compounds. It is also commonly used to manufacture a number of other chemicals both on a small scale and large commercial type lab operations. It is a volatile compound that can cause issues in the respiratory tract if inhaled directly. Must be used in a ventilation hood or ventilated area.

Carnoy’s Solution: Carnoy’s solution is a mixture of multiple volatile compounds that is used in numerous biological laboratory tests. Its uses range from the treatment of specific types of tumors, to the fixation of cell samples in the lab. The primary ingredients in this mixture are Ethyl Alcohol and Chloroform, both of which are extremely flammable and should be stored in the proper cabinet.

Ethyl Alcohol: This alcohol is also the alcohol commonly found in alcoholic beverages. It is used as a common laboratory solvent that can be used for numerous applications, and also an additive in gasoline referred to as gasohol. It is a category two flammable liquid, possessing chemical properties that produce a highly flammable liquid and vapor. It also is harmful if swallowed, and can cause eye damage and irritation. Due to the possibility of this being a possible form of substance abuse for the students, and the high flammability of the compound itself, it must be stored in a locked flammables cabinet.

Ethylene Glycol: Although Ethylene glycol is not inherently a high risk flammable compound, it is still considered a class one flammable compound, which still needs to be stored in the proper cabinet. Ethylene Glycol is also extremely poisonous, even at very small doses. It is common uses in the lab include the precipitation of proteins from solution, fractionation, purification, and crystallization.

Isopropyl alcohol: a very common compound found in many medicine cabinets, first aid kits, and cleaning supply cabinets. It most commonly used as an antiseptic in minor cuts and scrapes, or as a cleaning solution for white boards and electronics. Isopropyl alcohol also has numerous uses in the biology and chemistry classrooms. In biology it is used to extract DNA from solutions of cellular material, which separates the DNA from the rest of the solution. It can also be used to preserve and or subdue live specimens for examination, mainly in the dissection lab. It is also commonly used in the chemistry setting to react with various substances. Considered a category two flammable liquid, isopropyl alcohol is a liquid that is commonly stored incorrectly. It is so common, that it is often stored on the shelf in the stockroom, but it is highly flammable and needs to be relocated to its proper storage container.

Methanol: Methanol is another alcohol that needs to be stored in a flame retardant cabinet. A toxic compound, which can cause blindness when ingested in small amounts; or can cause death if larger quantities enter the body. It is used in the synthesis of many organic compounds in the lab. It is also a common laboratory solvent, and is also used in High Performance Liquid Chromatography. Methanol is a Category three volatile substance that must be stored within an OSHA approved flame retardant cabinet.

Mineral Oil: also commonly referred to as “baby oil” or Paraffin oil is commonly found in the chemistry stockroom to store highly reactive metals such as Calcium, Potassium, Cesium, and Sodium. It is used to prevent water vapor in the air from contacting these highly unstable pure metal samples. It is also considered a flammable compound that should be stored in the proper storage cabinet.

Petroleum Ether: A category two flammable liquid and carcinogen, Petroleum ether is a compound that must be stored properly, and handled with extreme care. Over time, exposure to this compound can cause mutagenicity in human cells, resulting in various types of cancer. A natural byproduct in the making of gasoline also referred to as “benzene”; this chemical is commonly used as a solvent for many organic chemistry applications. It can also be used as a glue or adhesive remover.

Tolulene: This compound is extremely dangerous for multiple reasons, the most immediate threat is it is a class two flammable liquid. Toluene is a common solvent that is able to dissolve paint, paint thinners, silicone, and rubber. It is also used to make numerous products in the lab; the most famous of these is Tri-Nitro-Toluene or more commonly referred to as TNT. It should never be stored with any acids, especially any of the nitrogen containing acids. It also has applications in making plastic polymers. Toluene also has been shown to cause reproductive failure and cell degeneration in the reproductive organs of lab animals. Safe handling and storage is a must for this chemical.

Xylenes: found in the group of aromatic hydrocarbons, this compound is one of the more flammable compounds found in the chemistry lab. It is a class three flammable liquid and vapor, which also is internally and externally toxic to human beings as well. Mainly used in histology for the fixation of cellular samples, it does have some chemistry applications as a solvent as well.

Storage of other hazardous materials such as acids (Class “E’ materials or Corrosives) is very similar to storing flammables in a special cabinet. My stockroom has a corrosives cabinet that is used to store all of my concentrated lab reagents. There are however, specific rules for storing acids in your stockroom that must be followed in order to ensure the safety of the students and faculty. Although the inert risk of flammability of pure acids and bases are not an issue, their seamless ability to react with other compounds stored near them is a danger in itself. Sometimes this requires certain lab reagents to be stored within a container or compartment separate from the rest of the acids within the cabinet. Special consideration needs to be made when determining what chemicals are going to be stored together.

Many corrosives are characterized by the following abbreviations:

C- Combustible liquid or solid

HT- Highly Toxic

O- Oxidizer

PEC- Potentially Explosive Chemical

T- Toxic

WR- Water reactive

An acid is a substance that donates hydrogen ions. Because of this, when an acid is dissolved in water, the balance between hydrogen ions and hydroxide ions is shifted. Now there are more hydrogen ions than hydroxide ions in the solution. This kind of solution is acidic.

A base is a substance that accepts hydrogen ions. When a base is dissolved in water, the balance between hydrogen ions and hydroxide ions shifts the opposite way. Because the base “soaks up” hydrogen ions, the result is a solution with more hydroxide ions than hydrogen ions. This kind of solution is alkaline.

Anything stored in a corrosives cabinet usually has a pH of below 2 and above 12 on the pH scale. A reagent with a pH lower than 7 is considered acidic and above 7 is considered basic. The scale runs from 0 (most acidic) to 14

Corrosive materials also have a myriad of side effect upon exposure, either directly, or from the toxic vapors they emit. Concentrated acids should always be diluted in a chemical hood and always handled with proper eye, body, feet, and hand protection. These concentrated chemicals are extremely dangerous.

Many people think that because something is on the basic side of the pH scale (pH of 7 through 14) that it is not as dangerous as a corrosive that is on the lower end of the pH spectrum. This is not the case; bases tend to cause more damage to tissues because they penetrate deeper into the skin, causing much more damage to the lower layers of skin on the body.

Below you will find a list of acids that are currently stored within my OSHA compliant Corrosives storage cabinet in my stockroom.

Ammonium Hydroxide: One of the least dangerous acids in my cabinet (although still very dangerous!). Very dilute ammonia solutions are sold over the counter as a house hold cleaning agent, but lab grade concentrated ammonia is very dangerous. Due to its high pH level, ammonium hydroxide solutions are alkaline. As a result, it is a severe eye, skin, and respiratory tract irritant that readily burns tissues it comes in direct contact with. Most commonly used in the chemistry lab to neutralize strong acids for proper disposal.

Hydrochloric Acid: hydrochloric acid is one of the most used lab reagents in the lab. This acid has a very wide use in high school chemistry. For me personally we use it for titrations involving acid base neutralizations. It is also commonly used in dilute forms for geological identifications of different types of rocks, or to show chemical weathering to simulate acid rain with different rock samples. Considered extremely corrosive in higher concentrations, it must be stored in a corrosives cabinet. It also must be diluted within a chemical hood because the fumes when adding the acid to water can severely damage the respiratory tract. Full protective equipment is an absolute must when handling this acid.

Nitric Acid: Most commonly used in the production of farm grade fertilizers, rocket propulsion, metal finishing, and explosives; Nitric acid is commonly found in high school chemistry labs as well commonly used for lab demonstrations and dehydration reactions. Extremely corrosive and fatal if swallowed, nitric acid is another extremely dangerous acid to handle and store. In addition to being stored within a corrosives cabinet, Nitric acid must be stored separately within the cabinet itself (My OSHA corrosives cabinet has a separate compartment to store nitric acid within). It is not to be stored with other acids, mainly ammonium hydroxide because of the inherent risk of explosive compounds being inadvertently formed during long term storage.

Sulfuric Acid: one of the most important industrial chemicals in the United States, more of this acid is made than all of the others combined annually. It is used to make many of the other acids mentioned earlier, along with the manufacture of fertilizers and manufactured goods. It is also the main component of traditional batteries, especially automotive batteries. For high school chemistry, it is used to react with many metals as lab demos, or to produce hydrogen gas for demonstration as well. Once again, another highly corrosive substance that needs to be stored in a corrosives cabinet. It also needs to be handled with extreme caution while also wearing all of the necessary protective clothing.

After reading this article, it is very apparent that student safety is the most important thing to consider when storing and handling these types of chemicals in the lab. Proper storage and safety drastically reduces the risks of injury or damage to the building. It is imperative that the instructor practices and teaches students the importance of how to handle these chemicals safely. This is just a very small list of all of the different types of hazardous compounds that may be found in a common chemistry lab. There are numerous others that are not mentioned in this article, so it is always important to keep MSDS sheets handy when an instructor or student is unsure of the risks involved with many of these chemicals. It is also extremely important that the building administrator be aware of where the MSDS sheets are located in the event of an emergency so that proper care can be taken during the situation. Stay safe and good luck!